This invention relates to lock-stitch sewing machines. In particular, it relates to a rotary hook for single-needle lock-stitch sewing machines.
Examples of prior art in rotary hook sewing machines can be found in U.S. Class 112, Subclass 231 of the U.S. Patent Classification System. Pertinent prior art includes U.S. Pats. Nos. 1,966,432, 2,830,550, 3,476,068 and 4,009,670, German Pat. No. 50727 and British Pat. No. 700,306. The prior art uses the standard bobbin having identical end plates and has one or more problems such as "stalling" of thread, low capacity, difficulty in threading, and difficulty in maintaining the appropriate tension.
One object of this invention is to provide a hook and bobbin assembly having higher thread capacity, ease of threading, self-adjusting tension, less stalling, and higher speed than the prior art.
Further objects and advantages of this invention will be apparent from the description and claims which follow taken together with the appended drawings.